The James Webb Space Telescope has detected an organic molocule in the atmosphere of a far flung exoplanet that could indicate the presence of life thriving in a vast global ocean, though further observations will be needed to confirm it.
The exoplanet K2-18 b is thought to orbit in the habitable zone of an alien star some 120 light-years from Earth in the constellation Leo. Earlier observations of the distant world, which is roughly 2.6 times bigger than Earth, had led some scientists to believe that it could belong to a newly discovered type of potentially habitable planets known collectively as ‘Hycean worlds’.
These planets are essentially mini-Neptunes, and boast hydrogen rich atmospheres and world-spanning oceans that have the potential to sustain microbial life. Now, a new study of K2-18 b using data harvested by the James Webb Space Telescope (JWST) has revealed more about the true nature of the alien planet.
Our @NASAWebb telescope detected carbon dioxide and methane in the atmosphere of a planet orbiting a faraway sun. The planet might have an ocean, but more observations are needed to determine whether it could support life: https://t.co/J8ub8PqwMG pic.twitter.com/SbgHjOO9Hv
— NASA (@NASA) September 11, 2023
Ordinarily, sub-Neptune worlds like K2-18 b are challenging to observe owing to the deluge of radiation pouring out from their parent stars. However, in the case of K2-18 b, the astronomers were able to capture light from the parent star that had travelled through the atmosphere of the orbiting planet.
“This result was only possible because of the extended wavelength range and unprecedented sensitivity of Webb, which enabled robust detection of spectral features with just two transits,” said Nikku Madhusudhan of the University of Cambridge, lead author of the paper describing the JWST observations accepted for publication in The Astrophysical Journal Letters. “For comparison, one transit observation with Webb provided comparable precision to eight observations with Hubble conducted over a few years in a shorter wavelength range.”
By analyzing the chemical signature imprinted in the starlight, the team were able to detect the presence of methane and carbon dioxide in the exoplanet atmosphere, which supported the theory that K2-18 b could indeed be a Hycean world.
The astronomers also discovered evidence of the rare molecule dimethyl sulfide in the light spectrum, which would be a strong indicator for the presence of life. On Earth, dimethyl sulfide is created solely as a byproduct of life, most commonly by marine bacteria and microscopic organisms known as phytoplankton.
"Our ultimate goal is the identification of life on a habitable exoplanet, which would transform our understanding of our place in the universe," explained Madhusudhan. "Our findings are a promising step towards a deeper understanding of Hycean worlds in this quest."
The astronomers warn that further observations with Webb will be needed to confirm the presence of the biomarker in the atmosphere of the alien world. It is also possible that the radiation from K2-18 b’s parent star could have made its potentially gigantic ocean too hot to sustain life as we understand it.
The team in charge of the JWST are planning to conduct follow-up observations of the ocean planet with the telescope’s Mid-Infrared Instrument (MIRI), which could shed further light on the true nature of the alien world.
"Our findings underscore the importance of considering diverse habitable environments in the search for life elsewhere," said Madhusudhan. "Traditionally, the search for life on exoplanets has focused primarily on smaller rocky planets, but the larger Hycean worlds are significantly more conducive to atmospheric observations."
Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer
